Spin-orbit coupling in the metallic and spin-liquid phases of Na4Ir3O8

TL;DR

This paper explores how spin-orbit coupling influences the electronic and magnetic phases of Na4Ir3O8, revealing effects on its metallic and spin liquid states, including enhanced Wilson ratio and temperature-dependent Hall effect.

Contribution

It derives an effective Hubbard model incorporating spin-orbit coupling for Na4Ir3O8 and analyzes its impact on both metallic and spin liquid phases, highlighting novel physical behaviors.

Findings

Enhanced Wilson ratio observed due to spin-orbit effects

Strong temperature dependence of the Hall coefficient

Spin-orbit coupling influences phase stability and electronic properties

Abstract

It has recently been proposed that Na4Ir3O8 is a weak Mott insulator at ambient pressure, supporting a three-dimensional spin liquid phase with a spinon Fermi surface. This proposal is consistent with recent experimental findings that the material becomes a metal upon increasing pressure or doping. In this work, we investigate the effect of the spin-orbit coupling arising from 5d Ir moments both in the metallic and spin liquid phases of Na4Ir3O8. The effective Hubbard model in terms of pseudospin j=1/2 Ir states is derived and its consequences to both metallic and spin liquid phases are studied. In particular, the model leads to enhanced Wilson ratio and strong temperature dependence of the Hall coefficient.